GATE 2021 MN – Question 60
A project has activities(duration days; predecessors): A(3; none), B(4; none), C(5; A, B), D(6; B), E(7; D), F(8; C, E), G(9; D), H(X; F, G). Total completion time is 30 days. Find integer X.
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Correct answer: 5 to 5
Explanation
Earliest finishes are A 3, B 4, C 9, D 10, E 17, F 25, G 19. H must wait until both F and G finish, so it starts on day 25. Completion at 30 requires X=30−25=5 days. The controlling chain is B–D–E–F–H.